Report - Oregon State Library: State Employee Information Center ...

2.0 OVERVIEW OF LIQUEFACTION-INDUCED DAMAGE
TO BRIDGE APPROACH EMBANKMENTS
AND FOUNDATIONS
2.1 INTRODUCTION
The reconnaissance reports of several recent earthquakes document numerous cases of
significant damage to bridge foundations and abutments from liquefaction-induced ground
failures. Additional documentation on the damage to highways, bridges, and embankments from
liquefaction of loose, saturated, cohesionless soils clearly points out the need to develop
improved criteria to identify the damage potential of both new and existing highway structures.
Lateral ground deformations due to cyclic loading have been a major source of bridge failures
during historic earthquakes. Most damage of this type occurs at river crossings where bridges are
founded on thick, liquefiable deposits of floodplain alluvium. Bridge piers and abutments are
usually transported riverward with the spreading ground. Associated differential displacements
between foundation elements generate large shear forces in connections and compressional
forces in the superstructure. These forces have sheared connections, allowing decks to be thrust
into, through, or over abutment walls or causing decks to buckle. In other instances, connections
have remained intact with the deck acting as a strut, holding tops of piers and abutments in place
while the bases of these elements are displaced toward the river (Youd 1993).
In the past four decades, there have been numerous reports on damage to bridge foundations as a
result of liquefaction. For example, liquefaction-induced ground deformations were particularly
destructive to highway and railway bridges during the 1964 Alaska Earthquake (Bartlett and
Youd 1992). Ninety-two highway bridges were severely damaged or destroyed and an additional
49 received moderate to light damage. Approximately $80 million in damage (1964 value) was
incurred by 266 bridges and numerous sections of embankment along the Alaska Railroad and
Highway (Kachadoorian 1968; McCulloch and Bonilla 1970). More recently, numerous bridge
failures occurred during the 1995 Hyogo-Ken Nanbu (Kobe) Earthquake (Shinozuka 1995;
Matsui and Oda 1996; Tokimatsu et al. 1998). The Harbor Highway, a newer route with modern
bridge structures located adjacent to Osaka Bay, suffered major damage as a result of severe
liquefaction and large soil movements. Every bridge on the Harbor Highway from Nishinomiya
to Rokko Island suffered damage and the highway was subsequently closed. Liquefactioninduced
ground deformations have caused similar damage in many recent earthquakes in Costa
Rica, Japan, and the Philippines. These reports clearly demonstrate the hazard associated with
the liquefaction of soils, and provide valuable case histories on the behavior of soils as well as
the structural response and modes of failure associated with damage to bridges.
The modes of damage observed during past earthquakes reflect numerous site-specific factors. In
addition to the seismic and geologic hazards, bridge design and construction has a significant
influence on the seismic performance. The ODOT bridge inventory includes over 2,600 bridges
9